A gas turbine engine typically includes a fan section, a compressor section, a combustor section, and a turbine section. Air entering the compressor section is compressed and delivered into the combustion section where it is mixed with fuel and ignited to generate a high-speed exhaust gas flow. The high-speed exhaust gas flow expands through the turbine section to drive the compressor and the fan section.
A low speed spool generally includes an inner shaft that connects the fan section and a low pressure compressor section to a low pressure turbine section. A high-speed spool includes an outer shaft that interconnects a high pressure compressor section and a high pressure turbine section. The low speed spool and the high speed spool are mounted for rotation about an engine central axis relative to an engine static structure via several bearing systems.
Bearings are mounted within bearing compartments that are sized to contain an adequate amount of lubricant such that the bearings operate efficiently. It is important to maintain proper lubrication so that the bearings do not overheat. Bearing compartment volumes have decreased as overall engine sizes have become smaller in an attempt to reduce weight while still providing the desired power output. As such, providing sufficient cooling for the bearing systems has become even more challenging.